Geomatics Chapter 2,3

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What is the purpose of a coordinate system?

Used to define points and orientation

What are geogrpahic coordinates and how are they used?

Used to define positionand orientation, change in location or relative distance between points on a sphere

Based on latitude and longitude

Equator

Formed by the intersection of a plain bisection of the earth at right angles to the axis of rotation

Meridians

Formed by the intersection of vertical planes passing through the center of the earth and the sphere

What is the approximate latitdue of Saskatoon?

58.1333 Degrees North

What is the approximate longitude of Saskatoon?

106.667 Degrees West

What is the approximated radius of the Earth? (Assume the Earth is a sphere)

6367272 m

Ecliptic

Path made by the Earth traveling around the sun

Perihelion

Closest point to the sun on the ecliptic path

Aphelion

Farthest point from the sun on the ecliptic path

Celestial Equator

The Vernal and Autumnal equinox are points on interesection between the ecliptic and celestial equator. This plane also pass through the sun

Azimuth

Azimuth is the angle measured clockwise from North

Formula for calculating latitude based on the lower or upper culmination:

Latitude=h+(90-declination)

Solar Day

The interval between two successive lower transits of the sun's center of the same meridian

How long does it take for the sun to move 15 degrees?

1 hour

Who proposed standard time?

Sanford Flemming

International Date Line

Imaginary line that seperates two calendar dates

Sidereal Time

The interval between two successive upper transits of the vernal equinox over the same meridian

One sidereal day is equal to how many solar days?

0.9973 solar days

A nautical mile equals how many:
Minutes of arc
Feet
Meters

1'

6076.65 feet

1852.16 m

Geodesy

Branch of mathematics which determines by obsservation and measurement the exact positions of points and areas of large portions of the Earths surface, the shape and size of the earth, and the variations of terrestrial gravity

In geodetic surveying, the computation of the geodetic coordinates of points are performed on what?

Performed on an ellipse as it closely approximates the size and shape of the earth

What is the geoid?

The geoid coincides with the surface to which oceans would conform over the entire earth of free to adjust to the effects of gravity and centrifugal force

Deflection of the Vertical

The angle between a plumb line (line perpindicular to the geoid) and a line perpindicular to the ellipsoid

What does physical geodesy do?

Utilizes measurements and characteristics of the Earths gravity field to deduce the shape of the geoid

Absolute Gravity

If the value of acceleration of gravity can be determined at the point of measurement directly

Relative Gravity

If only the differences in the value of the acceleration of gravity are measured between two or more points

What is the formula used for determing the orthometric elevation? What does each variable represent?

H=h-N

H=Orthometric elevation

h=Height of the ellipsoid measured from Earth's surface

N=Geodial height (undulation)

Valuable properties of a map are:

Shape

Area

Distance

Direction

When a map preserves shape it is said to be:

Conformal (orthomorphic)

Maps that preserve areas are good for:

Populations per square meter

Distribution maps (trees, tons of coal etc.)

Gnomonic Projection

Projection at the center of the earth. All great ciircles appears as straight lines

Lambert Conformal Conic Projection

Conical projection with two standard parallels that intersect the zone of interest at 1/6 of the zone width from the North and South zone limits

Meridians appear as straight lines converging towards the center of the cone

Mercator Map Projection

Projection of a globe onto a cylinder.

Merdians are equally spaced vertical lines

Parallels are horizontal line whose spacing increases towards the poles

Created to show a line of constant bearing on the the globe. Appears as a straight line on the projection known as a rhumb line

What is the scale factor for a mercator map projection?

Scale at latitude=(Scale at equator) x cos(latitude)

Properties of UTM Map Projections are:

UTM zones are 6 degrees wide

Reference ellipsoid is NAD 27 or NAD 83

Basis for 1:50000 topographic maps

Origin for latitude (northing) is the equator

Southern hemisphere given 10,000,000 as false northing at the equator

Origin for Easting is at the Central meridian of each zone

False Easting of 500,000 given to central meridian

North latitude= 84 degrees N

South latitude= 80 degrees S

At what longitude does the UTM zone numbering begin and how many zones are there?